U4084B Datasheet, PDF (1/26 Pages) TEMIC Semiconductors – Low-Voltage, Voice-Switched Circuit for Hands-Free Operation

U4084B
Low-Voltage, Voice-Switched Circuit for Hands-Free Operation
Description
The low-voltage, voice-switched speakerphone circuit
U4084B incorporates the features listed below. The ver-
satility of the device is further enhanced by giving access
to internal circuit points.
The block diagram shows amplifiers, level detectors,
transmit and receive attenuators operating in comple-
mentary functions, back ground noise monitors, chip
disable, dial tone detector and mute function etc.
Due to low-voltage operation, it can be operated either by
low supply voltage or via a telephone line requiring
4.0 mA typ. Further features are stand-alone operation
via a coupling transformer (Tip and Ring) or in
conjunction with a handset speech network, as shown in
figure 2.
Features
D Low-voltage operation: 3.0 to 6.5 V
D Attenuator gain range between
transmit and receive: 52 dB
D Four-point signal sensing for improved sensitivity
D Monitoring system for background-noise level
D Microphone-amplifier gain adjustable
D Mute function
D Chip disable for active/ standby operation
D Dial tone detector
D Compatible with the speaker amplifier U4083B
D Case: DIP24 or SO24
Benefits
D Fast channel switching enables quasi duplex
operation
D Low current consumption for high output volume
D Optimized U3800BM interface
TELEFUNKEN Semiconductors
1 (26)
Rev. A1, 31-Jan-97
Preliminary Information